PT-2026-61184 · Linux · Linux

CVE-2026-63867 · Published 2026-07-19 · Updated 2026-07-19

NVD

CVSS v3.1

8.2

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

In the Linux kernel, the following vulnerability has been resolved:

mptcp: close TOCTOU race while computing rcv wnd

The MPTCP output path access locklessly the MPTCP-level ack seq in multiple times, using possibly different values for the data ack in the DSS option and to compute the announced rcv wnd for the same packet.

Refactor the cote to avoid inconsistencies which may confuse the peer. Also ensure that the MPTCP level rcv wnd is updated only when the egress packet actually contains a DSS ack.

Fix

Related Identifiers

CVE-2026-63867

Affected Products

Linux

References · 8

• https://nvd.nist.gov/vuln/detail/CVE-2026-63867 · Security Note
• https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45 · Note
• https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43 · Note
• https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497 · Note
• https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef · Note
• https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510 · Note
• https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8 · Note
• https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f · Note